Selection of orthogonal chromatographic systems based on parametric and non-parametric statistical tests Review Article

The generalized pairwise correlation method (GPCM) with different statistical tests was applied to examine the similarity/orthogonality of the tested systems. Beside this, the Pearsonʹs (product moment) correlation coefficient, the Spearmanʹs rho and the Kendallʹs tau were also used as conventional correlation parameters. The Williams’ t-test (as a parametric statistical test), and the Conditional Fisherʹs, the McNemarʹs and the Chi-square tests (as non-parametric statistical tests) were used for hypotheses testing. Except for the selection using correlation coefficients all other measures are non-parametric. A new procedure was applied to establish orthogonality of the chromatographic systems. From the different correlation measures so-called orthogonality ratios were calculated. The ratios originating from GPCM with McNemarʹs test was found to be the best to select orthogonal (dissimilar) and similar systems. The method was compared with various alternatives to validate the findings (among others with the ratios from Pearsonʹs correlation coefficients). The non-parametric options for correlation coefficients (Spearmanʹs rho and Kendallʹs tau) are found not to be sensitive enough to define the orthogonality of these chromatographic systems.